To Draw the Volute
From this as centre and one part as radius describe a circle. Within this circle draw a square, having for a diagonal the diameter of the circle. Bisect the sides of the square and draw the diameters by joining the points of bi-section. Divide these diameters of the square into six and these points will be the centres for the segments of circles which form the volute. Vertical and horizontal lines drawn from the centres will define the extent of each segment.
No. 161. Ionic Capital, with angular volutes.
For small scale drawings the volutes are drawn free-hand, but for larger working drawings it is necessary to use some method such as that given here.
The angle formed by the meeting of the ovolo and the volute is masked by a detail of anthemion form.
The ends of the bolster between the volutes consist of concave or ogee curves, which are symmetrically arranged from a centre line; moulded ridges or conventional leaf detail decorate the centre.
The form of the Ionic capital, while suitable for a façade, requires some modification if it is to be carried round the side of a building, owing to the great dissimilarity in the front and side views. In this case the end volute of the capital at the angle of the building is projected forward at an angle of 45 degrees, and the side is then treated in the same way as the front.
In late Renaissance buildings this difficulty was overcome by making all the volutes project at angles of 45 degrees, so that the four faces of the capital were uniform. This entails the bolster being dispensed with, and the volutes, no longer connected laterally, spring directly from the top of the ovolo moulding, and the space between the springing lines is occupied by a husk.
No. 162. Ionic Capital. Detail of Angular Volute.
As the volutes make equal angles they conform more or less to a square plan. The plan of the abacus is composed of four concave curves with small straight intervals at the meeting angles. The general proportions for this form of capital are the same as for the bolster type.